[geos-devel] Re: [postgis-users] GEOS / Predicates Update

[Norman Vine]

David Blasby writes:
> 
> > But...  I can't help but wonder if the problem wouldn't automagically
> > disappear if we compiled the PostGIS code as C++ and made the
> > GEOS part of PostGIS a real C++ module that knew all about
> > handling exceptions
> 
> I have thought about this, but havent experimented with it.  I also 
> experimented with statically linking the c++ library into postgis, but 
> was unable to get it work (anyone know how to do it?).

You need to link with c++ not gcc
 
> It would be a good experiment to write a simple C++ plugin for 
> postgresql and see if it has any problems.  If this works, there 
> shouldnt be any difficult problems converting PostGIS to C++ - but it 
> could be time consuming.

Shouldn't be too much work as most of the existing code can be

#ifdef __cplusplus
extern "C" {
#endif
....
}

One thing I noticed whrn trying to compile the existing code with
C++ is that most of the allocs inside of PostGIS will need to be cast
appropriately  

i.e  instead of 
char *result = palloc(size);
char *result = (char *)palloc(size);

This should probably be being done anyway !

Another gottcha is in PostgesSQL it self and *requires* a change
that should probably be brought to the pgsql developers attention

postgresql-7.3.2-1\src\include\nodes\memnodes.h

typedef struct MemoryContextMethods
{
	void	   *(*alloc) (MemoryContext context, Size size);
	/* call this free_p in case someone #define's free() */
	void		(*free_p) (MemoryContext context, void *pointer);
	void	   *(*realloc) (MemoryContext context, void *pointer, Size size);
	void		(*init) (MemoryContext context);
	void		(*reset) (MemoryContext context);
	void		(*delete) (MemoryContext context);
                                    ^^^^^^^^^^
delete is a reserved word in C++ !!!

Cheers

Norman